A large amount of effort has been spent to control water and air pollution and has resulted in a number of devices and materials being produced. Noxious vapors and gases are a typical example of sources of air pollution which can make breathing difficult and unpleasant. To effectively clean air in large areas, mechanical filters and electronic cleaners are often used. These devices include air exchange filtration systems or electronically charged fields and plates to collect and remove particulate matter. The mechanical filters and electronic devices can be expensive to produce and require continuous maintenance thereby limiting their use. A further disadvantage of electronic air cleaners is that some of the devices produce ozone which is itself an air pollutant. Household odors such as cooking odors, pet odors and bathroom odors can be difficult to control. Numerous devices are presently on the market designed for deodorizing and freshening the air. These products are produced in many forms including, mist, blocks, liquids, powders and aerosol sprays. These products are generally effective for masking odors, but do not eliminate the odors or remove contaminants from the air.
Other solutions have been proposed to purify and freshen the air. For example, U.S. Pat. No. 1,737,532 discloses an air purifying and deodorizing device for use in refrigerators, toilets and sick rooms. A metallic container having a perforated surface and an adsorbent deodorizing material is placed within the area to be purified. The disclosed deodorizing material is a charcoal combined with other ingredients having germicidal qualities.
A further example of an air and water purifying device is disclosed in U.S. Pat. No. 5,224,975 to Purnell et al. This device is a canister having a perforated side wall and closed ends for containing a zeolite material. The canister has a limited number of openings for the exchange of air and water which limits its utility and effectiveness.
Accordingly, there is a continuing need in the industry for improved devices for purifying air and water.